Most people don't think twice about talking, texting or emailing on the go — sending waves of radiation into the environment and their bodies as they stay connected through mobile technology.

The bulk of research into cellphones and their base towers has found no definitive evidence that short-term use poses significant health risks to humans. So, policy makers have given industry the green light, allowing the use of wireless gear to explode around the world, to about five billion wireless subscriptions worldwide, by the World Health Organization's estimate.

Now that the technology has been widely used for a number of years, researchers have turned their attention to exploring possible effects of long-term exposure to the electromagnetic fields (EMF) the radiofrequency waves used to transmit cellphone communications create.

In May 2011, the WHO's International Agency for Research on Cancer did a review of existing research on the effects of exposure to such electromagnetic fields. It found that, for most cancers, the available evidence was inadequate to make any conclusions about risk.

In the case of glioma, a type of brain cancer, and acoustic neuroma, a slow-growing non-cancerous tumour in the inner ear that results in hearing loss, the existing evidence was limited. This means the group found that evidence of a causal relationship between cellphone radiation exposure and increased risk of developing one of those diseases was credible but could not rule out that chance or bias had played a role in establishing that relationship.

Nevertheless, the group found that in the case of glioma, the evidence was significant enough to warrant classifying radio frequency electromagnetic fields as "possibly carcinogenic to humans," a WHO category known as 2B, and to warrant further study of a possible link between wireless use and cancer risk, the group said.

To help put this in perspective, coffee and the pesticide DDT are also classified as "possibly carcinogenic to humans."

Earlier reviews of research done by the European Commission and by Swedish scientists, whose results were published in the journal Occupational and Environmental Medicine, found some evidence of increased relative risk of glioma and acoustic neuromas after more than 10 years of cellphone use. But these studies also said the majority of papers on the topic reported no connection between 10 years of mobile phone use and disease.

Another study — published July 27, 2011, in the Journal of the National Cancer Institute — looked at children from Norway, Denmark, Sweden and Switzerland, aged 7 to 19. It found that those with brain tumours were not statistically more likely to have been regular cellphone users than the control subjects.

Supporting data on either side of the debate is limited. Health Canada, the Food and Drug Administration in the U.S. and the European Union have based their cellphone regulations on the majority of evidence available so far.

Who's using wireless

Cellphone technology is already firmly ingrained in Canadian culture — especially in urban centres. More than 24 million of us used cellphones by the end of 2010, according to Health Canada.

The Canadian Wireless Telecommunications Association estimated 70 per cent of people in major urban centres in Canada are using wireless telecommunications technology, with some areas approaching the 80 per cent mark.

Placing voice calls on mobile devices rather than emailing or texting raises potential health concerns, because a user's level of exposure to radio frequency energy is higher during a call. Talking on a handset takes a lot more power than sending and receiving texts or other information, and the handset is usually held closer to your body when you're speaking than when you're using the device for other purposes.

The amount of radiation — in this case, electromagnetic waves emitted by handsets — that penetrates your body is based largely on how close the device is to your head during calls, the number of phone calls you make and how long your calls last.

Is it all in our heads?

According to the WHO, Health Canada, the FDA and the EC report, the bulk of scientific research has found no significant links between cellphone use and adverse health effects.

The EC research review did find some evidence that radio-frequency energy can cause local temperature changes in the brain, alter protein structure and expression, and affect neurotransmitter biochemistry.

Both the EC and the Occupational and Environmental Medicine studies found evidence that cellphone radiation might possibly influence some human behaviour, such as attention and memory.

The EC report also reviewed previous research into a possible link between mobile phone use and brain tumours in children and concluded that further investigation into the issue is "warranted" given the widespread use of cellphones among children and adolescents and the lack of relevant studies looking at possible effects on this group.

The U.K., Germany, Belgium, Israel, Russia, France and India advise that children limit their use of cellphones.

In October 2011, Health Canada slightly changed its previous guideline to encourage Canadians to limit cellphone calls, especially those under the age of 18.

Previously, Health Canada said people could limit their use if they were worried about a possible link between cellphones and cancer.

James McNamee, division chief for health effects and assessments in Health Canada's bureau of consumer and clinical radiation protection, said the agency was trying to be more proactive about its message for children.

"There has been relatively little science done on children and children's cellphone use, and children are going to be using these devices for a much larger period of their life span," McNamee said. "Their brains and immune systems are still developing."

Health Canada said cellphone users may take practical steps to reduce exposure, such as:

• Limit the length of cellphone calls.
• Replace cellphone calls with text messages or use "hands-free" devices.
• Encourage those under the age of 18 to limit the cellphone use.

EMF

With researchers lacking the timeline, and therefore the data, to take a definitive stand on the long-term health effects of mobile telecommunications, some organizations, such as members of the BioInitiative Report, the European Environment Agency, and the EMR Policy Group, say current laws regulating the use of electromagnetic devices should be reconsidered.

Their position, which they say follows "the precautionary principle," is that if we can't be certain something won't have a negative impact on our health, we should err on the side of caution.